Objective:To measure the index of toxicokinetics and toxicodynamics of chlorpyifos in Sprague-Dawley rats after single oral-dose exposure to chlorpyrifos(CPF),and study the characteristic of toxicokinetics and toxicodynamics of CPF. Methods:The adult female SD rats were randomly divided into 5 groups (including 1 control group and 4 treated groups) according to the weight. Each group has fifteen rats. The dose of chlorpyrifos is respectively 12.5 mg/kg,25 mg/kg,50 mg/kg,100 mg/kg. Blood samples were collected through arteria cruralis after single dose gastric gavage exposure at 1 h,3 h,6 h,12 h,and 24 h,then rats were killed and cortexes were collected. The concentrations of CPF and TCP(3,5,6-trichloropyridinol)at every five time point in plasma were determined by HPLC(high performance liquid chromatography),and acetylcholinesterase(AChE) activity was estimated by the Pureauto CHE. Results:The peak concentration of CPF and TCP first peak were observed at 3 h and 6 h,respectively,then declined. The maximum inhibition of plasma AChE was observed between 3 to 6 h. Maximum inhibition of cortex AChE occurred between 6 to 12 h. Both the plasm concentration of CPF and TCP were linear negatively correlated with the plasm AChE activity. The plasm concentration of CPF and TCP showed a linear positive correlation. Conclusion:Through this study,we obtain several indexes of toxicokinetics and toxicodynamics of CPF,and represent the characteristics. These results will provide useful information to the physiologically based toxicokinetics and toxicodynamics(PBTK/TD)model.